Major Vows to Withstand Party Loss : Britain: MP's unprecedented defection to Labor comes on eve of Tory meeting.

LONDON — British Prime Minister John Major said Sunday that the unprecedented defection of a Conservative member of Parliament to the Labor opposition will not distract him from the task of winning the next general election, due by mid-1997.

But Alan Howarth's shock move--he is the first Conservative ever to "cross the floor" of Parliament to join Labor--reduced Major's fragile majority in the 651-seat House of Commons to only five and dealt him a body blow on the eve of the four-day annual party conference, which starts Tuesday.

As Labor crowed over its notable new scalp, Major led his ministers in a damage-control exercise.

The prime minister, who has fought to heal the wounds in his divided party, said in a statement:

"I profoundly disagree with his analysis of the Conservative Party, but nothing will distract us from the task ahead. We have an election to win, and we intend to win it."

Howarth, 51, a former government minister, said Saturday that he quit because the Conservatives have moved to the right.

"The poor in Britain have not shared as they should have done in the growth of the nation's wealth, and are made to feel the object of indifference or even contempt by too many Tories," he said in his resignation letter.

"Rather than heal the divisions in our society, the Conservative Party seems intent on deepening them."

Howarth said that up to 40 other Conservative lawmakers share his concerns about the direction of the party but that he doubted others will quit.

The Conservatives have trailed Labor by more than 20 points in public opinion polls for the past 18 months and are now at record lows. Voters are angered by policy U-turns, party infighting over Britain's role in the European Union, allegations of sleaze and a string of sexual and financial scandals.

Major had hoped to regain momentum at this week's party conference, and on Sunday his Cabinet ministers promised a succession of policy announcements and initiatives to entice back supporters, particularly middle-class voters feeling insecure about jobs and property values.

Major has long been under assault from the right wing in the Conservative Party. In July he won a back-me-or-sack-me confrontation with them, resigning his party leadership and winning it back.

But Howarth's defection is the first serious public dissent by the party center, dismayed at what they see as Major's pandering to the right wing with talk of cuts in welfare spending, clampdowns on payments to the unemployed and anti-European rhetoric.

Howarth's departure also gave valuable ammunition to Labor, already in a buoyant mood after its own annual conference resoundingly backed centrist leader Tony Blair.